GB1161141A - Process for the preparation of Titanium Compounds which are substantially Free from Metallic Impurities - Google Patents

Abstract

1,161,141. Titanium compounds. MIZUSAWA KAGAKU KOGYO K.K. 19 Jan., 1967 [22 Jan., 1966 (2)], No. 2964/67. Headings C1A and C1N. A titanium oxy-phosphorus compound is produced by mixing a Ti compound with water and a phosphorus oxyacid or derivative thereof to give a liquid mixture which gels, forming granules during or after gelling without filtration, and extracting metal impurities from the granules. The Ti compound may be.-(a) An acid solution of ilmenite, iron sand slag, rutile, high Ti slag (compositions specified), gaseous or liquid TiCl 4 , or titanyl sulphate, e.g. sulphate process waste acid. The acid may be H 2 SO 4 , H 2 SO 3 (added as SO 2 gas), HCl, HClO 3 , HClO 4 , HNO 3 , oxalic, formic, methane sulphonic, or H 2 SO 4 +HNO 3 , and may be used at R.T. to B.pt. to dissolve the compound. If SiO 2 is present it is allowed to gel and is removed. (b) A Ti salt alone, e.g. TiCl 4 . (c) Amorphous Ti hydroxide, obtained by hydrolysis of acid solution (a) above by (i) heating under atmospheric or elevated pressure at 60-140‹ C., (ii) neutralizing, e.g. with NH 4 HCO 3 , or (iii) diluting with hot water. The gel so produced is filtered and may be heated at 100‹, 300‹, 500‹ or 650‹ C. The P compound may be H 3 PO 4 (e.g. crude acid), HPO 3 , H 4 P 2 O 7 , (HPO 3 ) 6 , H 5 P 3 O 10 , H 3 PO 3 , H 3 PO 2 ; anhydrides, e.g. P 2 O 5 ; halides or oxyhalides; salts of alkali metals, alkaline earth metals, ammonium, Zn, or Al, e.g. Na 2 HPO 4 .12H 2 O, NaPO 3 , Na 4 P 2 O 7 (NaPO 3 ) 6 , Na 5 P 3 O 10 , Na 2 HPO 3 , (NH4) 2 HPO 4 , Ca 3 (PO 4 ) 2 , and phosphorus ore. Formation of gel.-The P compound may be added at 0-80‹ C., optionally after the addition e.g. of H 2 SO 4 to the Ti solution, using 0À2-6 atoms P per atom Ti, to give a TiO 2 : P 2 O 5 mole ratio of 7.3 : 1 to 0.8 : 1. The mixture may form (a) a stable sol which is granulated while gelling, or (b) a gel which may be dried and is subsequently granulated. (a) Granulation of sol: it may be (i) poured or sprayed into an immiscible liquid (upwards or downwards), e.g. trichlorobenzene, kerosene alone or with dichloro or trichlorobenzene, or light oil, which may be agitated and maintained at 110‹ C., to give spheres 2-6 mm.; (ii) poured into a partitioned container, or tube or plate, and dried, e.g. at 100‹ or 115‹ C.; or (iii) dropped on to a belt conveyer or rotating drum or disc which may be heated, e.g. to 400‹ C., to give particles 70-200 Á. (b) Granulation of gel: it may be (i) cut or broken up, e.g. into flakes, (ii) extruded and air-dried; or (iii) thermally shrunk at 100‹ C. The grains may be 1À5-20 mm. in size. Extraction of impurities may be effected with water; acids, e.g. HC1, H 2 SO 4 , HNO 3 , H 3 PO 4 , H 2 SO 3 , HClO 3 , oxalic, acetic, formic, sulphonic or phosphonic; alkalis, e.g. NaOH, KOH, NH 4 OH, or lime water; organic solvents, e.g. methanol, ethanol, propanol, butanol, or acetone, with or without water or acid, e.g. H 2 SO 4 +methanol; complex formers, e.g. tributyl phosphate or EDTA; ion-exchange resins; or dialysis. A 2-stage treatment may be used, e.g. (a) dilute 0À1-10% acid then concentrated acid, (b) H 2 SO 4 at 60-70‹ C., then at 95‹ C., or (c) NaOH followed by H 2 SO 4 containing NaHSO 3 . Treatment with liquid may be effected by passing the liquid continuously through a column containing the gel, or by decantation. When alkali is used, the gel is converted into Ti hydroxide. Subsequent treatment.-The gel may be: (a) dried, broken up, and calcined at above 200‹ C., preferably at above 700‹ C.; (b) treated with P oxyacid or salt, e.g. H 3 PO 4 , to vary the TiO 2 : P 2 O 5 ratio, e.g. from 7.3 :1 to 2À2 : 1; (c) converted into Ti hydroxide by treating with NaOH or KOH, dried, crushed, and calcined at at least 500‹ C. to give TiO 2 ; or (d) treated with a salt of Al, Sn, Zn, Ca, or Zn and neutralized to deposit hydroxide. TiO 2 may be produced by dissolving the Ti hydroxide in HCl or H 2 SO 4 and hydrolysing. TiCl 4 may be produced by incorporating carbon into the starting solution or sol, forming Ti hydroxide from the gel, and treating the product with Cl 2 .